In order to further elucidate the organization of the primate auditory system at cortical and thalamic levels, the proposed research is aimed toward: (1) determining the afferent connections of the auditory responsive cortex in the superior temporal gyrus, (2) ascertaining the afferent and efferent connections of a polysensory area, the post-arcuate cortex and (3) determining the origin and distribution of afferents to cytoarchitectural divisions of the medial geniculate body. The connections of areas related to the auditory system will be investigated in Saimiri sciureus utilizing reduced silver methods and tritiated amino acids for anterograde tracings, and horseradish peroxidase for retrograde tracing of connections.